Note: Descriptions are shown in the official language in which they were submitted.
131519~
TOOL FOR TREATING SUBTERRANEAN WELLS
BACKGROUND OF THE INVENTION
This invention relates generally to the treatment of
subtlerranean wells and the like, and more particulary to a novel
and improved tool for the treatment of wells particulary suited
for use with one-piece coiled support tubing.
Prior ~rt
It is known to provide continuous lengths of coiled
tubing to support tools within subterranean wells, and through
which various fluids may be pumped to a tool mounted on the end of
the coil. United States Letters Patent No. 4,585,061 discloses a
system for inserting and withdrawing such coiled tubing with
respect to a well.
Since such tubing is a single, contlnuous tube, it
cannot be rotated and can only be raised and lowered. Therefore,
if such tubing is used to position a treatment tool within a well,
rotary movement cannot be used to control the various functions of
the tool. Consequently, it is difficult to employ such tubing
with a tool such as a straddle packer tool or the like for the
treatment of wells.
. .,,~,~.
131~19~
1 SUMMARY OF THE INVENTION
2 It is one important aspect of this invention to
3 provide a method and apparatus in which a treatment tool is
4 sequenced in its operation through a full treatment cycle by
S merely adjusting the load on the grippers which raise or
6 lower a one-piece tool support tube at the well head.
7 Further, the load on the grippers establishes that the tool
8 has been properly cycled.
9 In accordance with another aspect of this inven-
tion, a novel and improved time delay selector valve is
11 provided which can be operated from a remote location by
12 adjusting tension in a support tube. Further, a novel and
13 improved equalizer valve is provided.
1~ In accordance with still another aspect of this
invention, a novel and improved method is provided to form
16 cam surfaces on the interior of a tube which may be relative-
17 ly small in diameter and relatively long.
18 In normal operation of the illustrated embodiment
19 of this invention, the tool packers are first positioned
while deflated at the location within the well where treat-
21 ment is desired. By properly sequencing changes in the pull
22 on the tube, valves within the tool are moved to sequence the
23 tool operation. In the illustrated embodiment, straddle
24 packers are provided which, when inflated, isolate the
portion of the well between the packers from the remainder
26 of the well.
27 By adjusting the load on the tubing, the valves
28 within the tool are sequentially operated to:
29 (1) provide inflation of the packers;
(2) provide an injection test to determine if
31 the fluid can be injected into the sealed-
32 off portion of the well;
131~194
1 (3~ provide circulation to displace the non-
2 treatment fluid from the tube and spot the
3 treatment f luid at the tool;
4 (4) inject the treatment fluid into the strata
of the well between the packers; and
6 (5) after treatment is complet~d, deflate the
7 packers, allowing the tool to be reposi-
8 tioned at another treatment location, or
9 removed from the well.
The tool is often located many thousands of feet
11 down the well. Therefore, the supporting tubing is long and
12 quite heavy. Because of stretch in the tubing and the like,
13 movement of the tube at the surface of the well, either up
14 or down, does not necessarily produce a corresponding move-
ment of the tool. Therefore, the sequencing of the valves
16 in the tool is controlled by selectively changing the pull
17 or load on the tube at the surface. This provides the
18 operator with an accurate indication of the operation of the
19 valves to permit the operator to control the sequence of
operations of the tool.
21 In the illustrated embodiment, the tool is provided
22 with three interrelated valves. A drag valve is provided
23 with draq springs which engage the well surface. When the
24 tool is being lowered into the well, this drag valve remains
open; however, raising the tool causes the valve to move to
26 its closed position. A time delay sequencing valve is also
27 provided. The sequencing valve provides a dashpot or damper
28 which causes a time delay when the valve is moved in one
29 direction. The sequencing valve also provides a J-lock cam
system, permitting the positioning of the sequencing valve
31 in an intermediate position for circulation or spotting.
32 The three-position sequencing valve is also controlled by
33 adjusting,the load at the surface. The third valve is an
131~ 9~
4 71456-loO
equa]izer valve and is also operated at the surface by adjusting
the support tubing load.
With this invention, a reliable mechanical treatment
tool is provided which is sequenced in its operation without
rotation of the supporting tube and which can be used to perform
multiple treatment sequences at various locations in the well
without being removed from the well.
Also in the illustrated embodiment, the required J-lock
internal camming surfaces are formed by a novel and improved
method. These camming surfaces are cut in the outer surface of a
cylindrical mandrel. The mandrel is then positioned within an
outer tube and is button-welded to an outer tube through holes
formed in the tube. The center of the mandrel is then bored out,
leaving only the camming surfaces which are secured to the outer
tube by the button welds.
According to a broad aspect of the invention there is
provided a system for treating subterranean wells comprising an
elongated treatment tool having inflatable packers, a support
tube connected to one end of said tool operable to lower said tool
from a well head into a well and to supply liquid to said tool,
said tool providing valve means operable in response to changes in
tension in said tube and without rotating said tube to
sequentially:
(a) inflate said packers to isolate one portion of said well
from the remaining portions thereof and to lock said tool against
movement along said well;
(b) inject treatment fluid supplied to said tool through
said support tube into said one portion of said well; and
, ., i
~31~19~
4a 71456-100
(c) deflate said packers permitting further movement of said
tool along said well.
According to another broad aspect of the invention there
is provided a valve for tools used in subterranean wells,
comprising first and second elongated tubular housing members
connected for telescoping movement relative to each other between
an extended position and a compressed position, piston means in
one of said housing members movable relative thereto between a
first position and a second position, said valve being open
between the interior of said housing and the exterior thereof when
said housing members are in said extended position and said piston
means is in said first position, said valve being closed when said
housing means are in said compressed position or said piston means
is in sald second position, said valve being connected to a
treatment tool having inflatable packer means, said valve
operating to deflate said packer means when said housing members
are in said extended position and said piston means is in said
first position.
According to another broad aspect of the invention there
is provided a valve for tools used in subterranean wells,
comprising first and second elongated tubular housing members
connected for telescoping movement relative to each other between
an extended position and a compressed position, piston means in
one of said housing members movable relative thereto between a
first position and a second position, said valve being open
between the interior of said housing and the exterior thereof when
said housing members are in said extended position and said piston
means is in said flrst position, said valve being closed when said
.
131~9~
4b 71456-100
housing means are in said compressed position or said piston means
is in said second position, said housing members providing
pressure balancing means preventing fluid pressure therein from
moving said housing members to said extended position from said
compressed position.
The above and other aspects of this invention are
illustrated in the accompanying drawings, and are more fully
disclosed in the following specification.
BRIEF DESCRIPTION OF THE DRA~INGS
Figure 1 is a schematic representation of an entire well
treatment system in accordance with the present invention;
Figure 2 is a fragmentary, enlarged, longitudinal
section, taken at the upper end of the tool and illustrating the
equalizing valve provided by the tool;
'3~1'i,~.,'~,
~31~9~
1 FIG. 3 is a fragmentary, longitudinal cross section
2 of a portion of the tool immediately below the equalizing
3 valve illustrated in FIG. 2 and illustrating the drag valve
4 portion of the tool;
FIG. 3a is an enlarged, fragmentary, longitudinal
6 section illustrating the structural detail of the valve
7 portion of the drag valve;
8 FIG. 4 ls a fragmentary, longitudinal section
9 illustrating a portion of the tool immediately below the drag
valve illustrated in FIG. 3, whlch includes a J-lock assembly
11 and a dashpot or time delay assembly;
12 FIG. 4a is an enlarged, fragmentary, longitudinal
13 section of the J-lock assembly;
14 FIG. 4b is a rolled-out view of the ~-lock cam
structure as it would appear when viewed from the longitudi-
16 nal centerline of the tool;
17 FIG. 5 is an enlarged, fragmentary, longitudinal
18 section of the portion of the tool including the time delay
19 or dashpot assembly;
FIG. Sa is a cross section taken along line Sa-Sa
21 of FIG. 5;
22 FIG. Sb is an enlarged, fragmentary section taken
23 along line Sb-Sb of FIG. Sa, illustrating the flow control
24 orifices;
FIG. 5c is an enlarged, fragmentary section taken
26 along line 5c-5c of FIG. 5a, illustrating the back check
27 valve and pressure relief valve;
28 FIG. 6 is a fragmentary, longitudinal section of
29 the selector valve in the run-in position in which the
packers are inflated or deflated;
131519~
1 FIG. 6a is an enlarged, fragmentary, longitudinal
2 section of a portion of the selector valve illustrating the
3 structural detail thereof;
4 FIG. 6b is an enlarged, fragmentary section similar
to FIG. 6a, but illustrating the selector valve in the
6 spotting or circulating position;
7 FIG. 6c i5 an enlarged, fragmentary section similar
8 to FIGS. 6a and 6b, but illustrating the selector valve in
9 the injection position;
FIG. 7 is an enlarged, fragmentary section illus-
11 trating the connection of the packer subassembly to the
12 selector valve;
13 FIG. 8 is a longitudinal section of a portion of
14 the packer subassembly, illustrating one of the two spaced
packers;
16 FIGS. 9 through 14 are schematic illustrations of
17 the tool as it is progressively operated through one complete
18 cycle of operation of injecting treatment fluid into a
19 selected strata of a well;
FIG. 9 schematically illustrates the tool in the
21 run-in position;
22 FIG. 9a schematically illustrates the condition of
23 the J-lock assembly during run-in;
24 FIG. 9b illustrates the string weight provided by
the weighing scale during run-in;
26 FIG. 10 schematically illustrates the tool in the
27 packer inflation condition, and FIGS. lOa and lOb illustrate
28 the J-lock assembly position and weight scale reading corre-
29 sponding to the condition of FIG. 10;
13~19~
1 FIG. 11 schematically illustrates the tool in the
2 injection test position, and FIGS. lla and llb illustrate
3 the corresponding J-lock assembly position and the weight
4 scale reading;
FIG. 12 schematically illustrates the tool in the
~ spotting or circulating position, and FIGS. 12a and l?b
7 correspondingly illustrate the J-lock assembly and weight
8 scale reading;
9 FIG. 13 schematically illustrates the tool in the
injecting position, and FIGS. 13a and 13b illustrate the
11 corresponding condition of the J-lock assembly and the weight
12 scale reading;
13 FIG. 14 schematically illustrates the tool in the
14 deflation position, and FIGS. 14a and 14b correspondingly
illustrate the J-lock assembly and the weight scale reading;
16 and
17 FIGS. 15 through 15c schematically illustrate the
18 production of the internal camming surfaces provided by the
19 J-lock assembly.
13151~
1 DETAILED DESCRIPTION OF THE DRAWINGS
2 FIG. 1 schematically illustrates the entire well
3 treatment system in accordance with the present invention.
4 The system includes a treatment tool 10 connected to one end
of a one-piece, flexible tube 11 which functions to position
6 the tool 10 at a desired location in a well 12. The tube 11
7 also functions to supply fluid to the tool 10. The tool in
8 accordance with the present invention is particularly suited
9 for use with one-piece support tubing because it does not
require rotation for its operation. However, the tool can
11 also be used with support tubes consisting of connected
12 tubing sections.
13 The opposite end of the tube is coiled and stored
14 on a drum 13 and passes from the drum 13 through powered
grippers 14 which function to control the extension or
16 retraction of the tube to raise and lower the tool 10 within
17 the well 12. Connected to the grippers 14 is a weight
18 measuring scale 16 which permits the operator to determine
19 the weight of the tube 11 and the tool 10 being supported by
the grippers 14 at any given time.
21 When the string, consisting of the tube and the
22 tool, is being lowered into the well 12, the frictional drag
23 of the string along the surface of the well reduces the load
24 supported by the grippers 14 and provides a run-in weight.
When the string is being raised, the frictional drag in-
26 creases the tension in the tube and provides a pull-up weiqht
27 or lifting weight. These weight differences are recorded by
28 the operator when the toGl is positioned for treatment, and
29 are utilized in the control of the tool, as discussed oelow.
In addition, the system includes a measuring device
31 17 which engages the surface of the tube and provides the
32 operator with an indication of the length of the string, and
33 consequent~y an indication of the position of the tool within.
1315~9~
9 71456-100
the well. Reference should be made to U.S. Patent No. 4,585,061.
suPria, for a detailed description of a typical system for
controlling the raising and lowering of the string within the
well.
In addition, the system includes a pump 18 connected
through a valve 19 to selectively connect the valve to a reservoir
of inflation fluid 21 or a reservoir of treatmen~ fluid 22. The
output of the pump is connected to the end of the tube 11 on the
drum 13, so that either inflation fluid or treatment fluid can be
pumped down the tube 11 to the tool 10, as descried below.
Because the tool is often lowered very great distances
down a well, and because the tube 11 tends to ~tretch or contract
when the tenslon thereln ls changed, the tool 10 ln accordance
with the present invention is sequenced through its various
operating conditions based upon adjusted loads on the grippers 14
as indicated by the weight scale 16. The control of the tool does
not require rotary control movement, and is not affected by
variations in the stretch of the tube 11 extending along the
length of the well 12.
Figures 2 through 6 are fragmentary sectlons which
cooperate to illustrate the entire tool 10 in accordance wlth this
invention. These fragmentary sections are taken from the top of
the tool at progressive intervals along the length of the tool,
with Figure 2 illustrating the upper portion of the tool, Figure 3
illustrating the next portion of the tool, and Figures 4 through 6
illustrating progressively lower portions of the tool.
Figure 2 illustrates,an equalizing valve assembly 26
which functions during the deflation portion of the cycle of the
1 31519~
9a 71456-100
tool operation to relieve the pressure within the tool and
equalizes the internal pressure with the environmental pressure
surrounding the tool. Immediately below the equalizing valve
assembly 26 is a drag valve assembly 27
'~ ''
131519~
1illustrated in FIGS. 3 and 3a. The drag valve assembly 27
2provides a plurality of leaf springs 28 which resiliently
3~ress against the surface of the well to provide a frictional
4engagement which resists movement of the drag valve with
5respect to the well when the tool is raised or lowered within
6 the well.
7Immediately below the drag valve assembly 27 is a
8J-lock cam system 29 illustrated in FIG. 4. As described in
9detail below, this J-lock cam system cooperates with a time
10delay dashpot assembly 31, also illustrated in FIG. 4. An
11enlarged, fragmentary section of the J-lock cam assembly 29
12is illustrated in FIG. 4a and an enlarged, fragmentary
13section of the time delay dashpot assembly 31 is illustrated
14in FIG. 5. This time delay dashpot assembly 31 permits the
i5operator to position the selector valve in one of three
16selected operating conditions, as discussed in detail below.
17Positioned immediately below and connected to the
18 time delay dashpot assembly 31 is a selector valve assembly
1932, illustrated in FIG. 6. The selector valve assembly 32
is a three-position valve. In one position, it connects the
Zlpressure within the tool to inflatable packers 33, one of
22which is illustrated in FIG. 8. In a second position of the
23selector valve assembly 32, supply pressure to the tool is
24connected to circulation ports 35, as illustrated in FIG. 6b.
25In such second position, the portion of the well between the
25packers is also connected to the circulation port 35 to
27equalize the pressure of the portion of the well between the
28packers and the well portion above the packers. In the third
29position, the selector valve assembly 32 connects the supply
30pressure to the tool to a passage 34 (illustrated in FIG. 6)
31for the injection of the treatment fluid into the strata of
32the well between the packers 33.
ll 131519~
1 The Equalizing Valve
2 The equalizing valve, best illustrated ln FIG. 2,
3 provides an upper housing assembly 41 and a lower housing
4 assembly 42. The upper housing assembly is connected to the
lower end of the tube 11 which supports the entire tool 10.
6 Normally, an adjustable pressure relief valve and a check
7 valve (neither of which is illustrated) are provided at the
8 lower end of the tube between the tube 11 and the upper
9 housing assembly 41 to preven~ backflow of liquid up along
the tube 11 and also to protect the system from overpres-
11 surization. Since such back check valves and adjustable
12 relief valves are known to persons skilled in the art, they
13 are not illustrated herein.
14 The upper housing assembly 41 includes a tubular
connector 43 threaded into the end of an elongated housing
16 member 44 which cooperates with the connector 43 to define
17 a cylinder chamber 46 and provides a tubular extension 47.
18 The lower end of the tubular extension 47 is threaded into
19 a balancing piston 48, which, in turn, is provided with a
tubular extension 49.
21 The lower housing assembly 42 includes an outer
22 tube member 51 providing a seal 52 at its upper end engaging
23 the outer surface of the tubular extension q7. The lower end
24 of the outer tube member 51 is threaded onto a tubular
coupling member 53. The tubular extension 49 of the balanc-
26 ing piston 48 extends through a seal 54 into a central
27 passage 56 in the tubular member 53. The lower end of the
28 member 53 is threaded into an upper connector 72 of the drag
29 valve assembly 27.
The two housinq assemblies 41 and 42 are connected
31 for telescoping movement between an extended or run-in
32 position in which the balancing piston 48 is in engagement
33 with a shoulder 57 on the outer tube member and an inward
12 1315~ 9~
1 telescoped position in which the balancing piston 48 engages
2 the end 55 of the tubular member 53.
3 A centrally located, tubular piston member 58
4 provides a piston head 59 within the cylinder chamber 46 and
a tubular rod portion 61 extending through the balancing
6 piston 48 and a seal 62 therein. In the run-in position, the
7 friction of the sea~s 62 maintains the piston member 58 in
8 the upper position in which the piston head 5g engages the
9 lower end of the tubular connector 43. In such position, an
orifice or port 63 connects the interior of the tubular rod
11 portion 61 to the interior of the tubular extension 47.
12 Further, when the two housing assemblies 41 and 42 are in
13 their extended position, a port 64 provides communication
14 between the interior of the tubular extension 47 and the
surrounding portion of the well. Therefore, in the run-in
16 position illustrated in FIG. 2, fluid pumped down the tube
17 11 to the tool 10 is vented to the surrounding portion of the
18 well through the ports 63 and 64.
19 However, the equalizing valve 26 is structured so
that when the flow of~fluid into the tool exceeds a predeter-
21 mined amount, such as about 0.2 barrel per minute, the equal-
22 izing valve is closed. In order to provide such closing
23 action, the port 63 is sized to be substantially smaller than
24 the port 64. When the flow rate of fluid to the tool is
increased, a pressure drop occurs through the port 63 which
26 is sufficient to cause a differential pressure across the
27 piston head 59. This causes the piston head 59 to be moved
28 down along the upper housins assembly 41 a sufficient dis-
29 tance to move the port 6~ past the seal 62 in the balancing
piston 48 to close the equalizing valve 26.
31 The equalizing valve is also closed when the two
32 housing assemblies 41 and 42 are telescoped together to move
33 the port 64 past the seal 52 in the outer tubular member 51.
34 Movement of the two housillg assemblies 41 and 42 to the
13
13l~l9~
1 closed or fully telescoped position, however, causes the
2 lower end of the tubular rod portion 61 to engage a shoulder
3 at the lower end of the passage 56. This also functions to
4 reposition the piston member 58 in its upper position within
the upper housing 41 in which the port 63 is above the seals
6 62 and the balancing piston 48.
7 The balancing piston 48 functions to prevent high
8 pressure within the tool from extending the two housing
9 assemblies 41 and 42. In balancing operation, high pressure
within the tool is communicated to the upper side of the
11 balancing piston 48 through a port 66. A port 69 maintains
12 the lower side of the balancing piston at environmental well
13 pressure. The high pressure on the upper side of the balanc-
14 ing piston produces a downward balancing force on the upper
housing assembly 41, counteracting the pressure-induced force
16 tending to cause the ùpper housing assembly 41 to move up
17 relative to the lower housing assembly 42.
18 The Drag Valve
19 Referring now to FIGS. 3 and 3a, the drag valve
assembly 27 includes an upper tubular member 71 threaded at
21 its upper end into the coupler 72 which connects with the
22 equalizing valve assembly 26. A lower tubular member 73 is
23 threaded into the lower end of the upper tubular member 71.
24 An enlarged portion 74 is provided at the lower end of the
upper tubular member 71.
26 Positioned around the two tubular members 71 and
27 73 is a sleeve assembly 75 consisting of an upper sleeve 76
28 and a lower sleeve 77. The upper end of the lower sleeve 77
29 is provided with an enlarged portion 80 which cooperates with
the end of the upper sleevQ to provide a chamber 79 enclosing
31 the enlarged portion 74.
14
1 Mounted on the sleeve assembly 75 are a plurality
2 of leaf springs 28 which are arched in an outward direction
3 to provide a resilient engagement with the surface of the
well 12 and produce a frictional drag with respect to the
well which resists movement of the sleeve assembly with the
6 tool as the tool moves either up or down along the well.
7 During the run-in, the frictional drag provided by the
8 sprlngs 28 causes the sleeve assembly 75 to move to an upper
9 position relative to the tool, in which the enlarged portion
74 engages a shoulder 81 in the sleeve assembly 76. When
11 the tool is raised, the frictional engagement between the
12 springs 28 and the well surface resists upward movement of
13 the sleeve assembly 75 with the tool, and the sleeve assembly
14 assumes a lower position in which the enlarged portion 74
engages the end 82 of the upper tubular member 71.
16 The lower ends of the springs 28 are mounted in a
17 collar 83 which is slidable along the sleeve assembly 75 to
18 permit the springs to flex in and out so that they can follow
19 the contour of the wall of the well and maintain resilient
frictional engagement therewith. The springs 28 are rela-
21 tively long so that they can extend a substantial distance
22 to engage the well casing after passing through a relatively
23 small diameter production tube.
24 Threaded onto the lower end of the sleeve assembly
75 is a valve sleeve member 84 which is longitudinally
26 movable relative to the lower tubular member 73 and provides
27 spaced seals 86 which dynamically seal with the outer surface
28 of the lower tubular memher 73. During the run-in of the
29 tool, in which it is lowered into the well, the sleeve valve
member is held in its upward position by the frictional
31 engagement between the leaf springs 28 and the ~ell surface,
32 and in such position the lower seal 86 is above ports 87 in
33 the lower tubular member. Therefore, the drag valve assembly
34 27 is in a,n open position, ailowing circulation of liquid-
131519~
1 pumped down into the tool 10 through the tube 11. However,
2 if the tool is raised, the frictional engagement between the
3 springs 28 and the well surface causes the sleeve valve
4 member 84 to move down relative to the inner tubular members
to close the ports 87. Therefore, the drag valve is respon-
6 sive to the direction of movement of the tool 10 and is open
7 when the tool is being lowered in the well and closed when
8 the tool is being raised.
9 The J-Lock Assembly
The J-lock assembly 29 is illustrated in FIGS. 4,
11 4a, and 4b. FIG. 4b is a rolled-out view of the J-lock cam
12 structure illustrating the cam structure as a plane as it
13 would appear from the central longitudinal axis of the tool.
14 The lower tubular member 73 extends beyond the
lower end of the drag valve 27 to an end 91 which is thread-
16 edly connected to an intermediate tubular member 92. Posi-
17 tioned between a shoulder 93 on the tubular ~ember 73 and the
18 upper end of the intermediate tubular member 92 is a cam
19 follower ring 94 which is free to rotate around the central
axis of the tool but is held against axial movement rela~ive
21 to the tubular members 73 and 92. The cam follower ring 94
22 provides a projection 95 extending radially outward from the
23 ring.
24 Positioned around tne tubular member 73 is a J-lock
cam sleeve assembly 96 threaded into a gland ring 97 at its
26 upper end and into a cylinder sleeve 98 at its lower end.
27 The J-lock cam sleeve assembly 95 is axially movable along
28 the tubular members 73 and 92 and is provided with a camming
29 surface 99 shaped as best illustrated in FIG. 4b. The
follower projection 95 engages the camming surface 99 and
31 moves with the selector valve assembly between three operat-
32 ing positio,ns, as described 7n detail below.
i6 131~194
1 Referring to FIG. 4b, the cam surface 99 includes
2 an upper pocket 101 and a lower pocket 102. During the run-
3 in of the tool, the follower projection 95 is positioned in
4 the upper pocket 101.
The cam surfaces are shaped so that if the tubular
6 members 73 and 92 move downwardly relative to the J-lock cam
7 sleeve assembly 96, the follower projection 95 moves directly
8 down along a first path 103, indicated by direction arrows,
9 until it engages an inclined camminq surface 99a, along which
it moves into the pocket 102, as indicated at 95a.
11 If the follower projection 95 is in the lower
12 pocket 102 and the tubular members 73 and 92 are raised
13 relative to the J-lock carn sleeve assembly 96, the follower
14 projection 95 engages the inclined underside 99b of a first
island cam portion 104 along which it moves along a second
16 path 106. As the movement continues, the follower projection
17 moves along a vertical cam portion 99c into engagement with
18 an inclined cam surface portion 99d and up alongside a second
19 island cam portion 107. The line 108 indicates the relative
position between the J-lock cam sleeve assembly 96 and the
21 tubular members 73 and 92 above which flow-restricting
22 orifices commence to operate to resist the movement of the
23 follower projection 95 in an upward direction. This damping
24 or time delay function and the structure for producing it are
discussed in detail below.
26 After passing the position indicated by the line
27 108 a position is reached at 110 before reaching a position
28 in alignment with the upper end of the second island 107.
2~ The direction of re]ative movement is then reversed by
reducing the tensiori in the support tube 11. The follower
31 projection 95 then moves down along the upper surface 99e and
32 drops into a J-]ock pocket 99g to hold the selector valve in
33 an intermediate position. In that position, circulation of
1 31~9~
1 fluid through the tool is provided, as discussed below. On
2 the other hand, if the relative movement is not reversed, the
3 follower projection 95 returns to the upper pocket 101.
4 The movement path 109 indicates the path of the
5 follower projection 95 to the J-lock pocket 99g.
6 Once in the J-lock poc~et 99g, upward movement of
7 the follower projection 95 relative to the J-lock cam sleeve
8 assembly 96 causes the follower projection 95 to move verti-
9 cally upward along the path 111 and along the underside 99h
ln of the second island cam portion 107 past the position
11 indicated by the line 108. If such upward travel is contin-
12 ued, the follower projection 95 moves into the upper pocket
13 101.
14 On the other hand, if such upward travel is re-
15 versed, the follower projection 95 moves into engagement with
16 the inclined cam surface 99i and returns to the lower pocket
17 102.
18 With this structure, the selector valve described
19 in detail below can be moved in such a way that the valve can
be moved to either extreme position from the J-lock pocket
21 99g by merely timing the increased tension force applied to
22 the support tube 11.
23 The Time Delay Dashpot Assembly
24 The time delay dashpot assembly 31 is best illus-
25 trated in FIG. 5, and fragmentary, enlarged sections thereof
26 are illustrated in FIGS. 5a through 5c. Referring first to
27 FIG. 5, the cylinder sleeve 98 provides an upper cylinder
28 portion 116 extending from the location 117 to the location
29 118. Below the location 118, which is the lower end of the
upper cylinder portion 116, the cylinder sleeve provides a
31 second cylinder portion 119 having a diameter greater than
18
1315194
1 the diameter of the upper cylinder portion 116. The two
2 cylinder portions 116 and 119 are filled with liquid isolated
3 from the remainder of the tool~
4 Threaded onto the lower end of the intermediate
tubular member 92 is a damper piston assembly 121. Such
6 assembly includes a tubular piston head member 122 providing
7 a piston head portion 123. The piston head assembly 121 is
8 si~ed to fit the upper cylinder portion 116 with a close fit
9 but providing clearance with the lower cylinder portion 119.
As best illustrated in FIG. 5a, the piston head
11 portion 123 is provided with four flow control devices
12 peripherally spaced around the piston head portion. The
13 first flow control device 126 is a first orifice assembly.
14 The second flow control dev,ce 127 is a second orifice
assembly. A back check valve assembly 128 constitutes the
16 third flow control device, and a pressure relief valve
17 assembly 129 constitutes the fourth and last flow control
18 device.
19 Referring now to FIG. Sb, the first flow control
device 126 is open to the lower side of the piston head
21 portion 123 through a passage 131 and a lateral port 132.
22 However, the orifice assembly 127 is open through a through-
23 passage 133. The piston head assembly also includes a sleeve
24 valve member 134 which is resiliently biased toward the
piston head portion 123 by a set of springs 136. In its
26 normally extended position, the sleeve valve 134 positions
27 a seal 137 above the lateral port 132. Therefore, the
28 orifice assembly 126 is open to the two sides of the piston
29 head portion 123. However, when the differential pressure
across the sleeve valve 134 reaches a predetermined value,
31 the force of the spring set 136 is overcome and the sleeve
32 valve moves downwardly until the seal 137 is positioned below
33 the port 132. In such position, the orifice assembly 126 is
34 closed by the cooperation of the seal 137 and the seal 138,
lg 131~19~
1 and further flow through the orifice assembly 126 is pre-
2 vented. The seals 138 also provide the seal for the piston
3 assembly 121 with the upper cylinder portion 116.
4 The shifting of the sleeve valve 134, however, does
not affect the operation of the orifice assembly 127. With
6 this two-orifice structure, two rates of damping are pro-
~ vided. The orifice assembly 126 provides a relatively large
8 orifice allowing relatively rapid movement of the piston
9 assembly. However, when the sleeve valve shifts to its
operating closed position, the orifice assembly 126 ceases
11 to function and all of the flow must occur through the
12 orifice assembly 127; Such orifice assembly provides a
13 smaller orifice, so the rate of movement of the piston
14 assembly in the damping mode is quite slow, as discussed in
greater detail below.
16 As illustrated in FIG. 5c, the check valve assembly
17 128 connects the two sides of the piston to allow the piston
18 to move downwardly in a substantially unrestricted manner.
19 Therefore, the orifice assemblies 126 and 127 provide re-
stricted rates of movement only in the upward direction
21 relative to the cylinder sleeve 98. The pressure relief
22 valve 129 performs a safety function of allowing downward
23 movement of the cylinder sleeve 98 relative to the piston
24 assembly. In the event that the orifices become clogged,
the pressure relief valve allows movement of the tool to a
26 deflate position so that the tool can be retrieved.
27 The lower end of the piston head member 122 is
28 threaded into the upper end of a tubular connector 140. The
29 connector member is also threadedly connected to a tubular
valve member 141 which extends through a ring gland 142
31 (illustrated in FIG. ~a) providing inner and outer seals 143.
32 The ring gland 142 is free to slide longitudinally through
33 a limited distance. 20rts 144 maintain the lower side of the
34 ring gland 142 to environmental pressure. The gland
13~19~
1 functions to compensate for changes in volume of the damper
2 liquid due to changes in pressure and temperature as the tool
3 is lowered into the well.
4 When the piston head assembly 121 is located within
the lower end enlarged cylinder portion 119, clearance is
6 provided around the piston head assembly and the piston head
7 assembly can move freely. However, when the piston head
8 assembly 121 enters the upper cylinder portion 116, a dynamic
9 seal is provided between the piston head assembly and the
cylinder wall and darping or ~ime delay is provided to
11 prevent rapid movement of the piston head assembly up along
12 the cylinder wall.
13 The Selector Valve Assembly
14 The selector valve assembly is best illustrated in
FIGS. 6 through 6c, and includes an outer tubular housing
16 member 146 mounted at its upper end on the cylinder sleeve
17 98 and extending downwardly therefrom. A tubular inner
18 housing member 147 is threaded at its lower end into the
19 outer housing member 146 substantially ad~acent to its lower
end and cooperates with the outer housing member 146 to
21 provide a valve housing assembly which is fixed against
22 longitudinal movement relative to the cylinder sleeve 98.
23 The tubular valve member 141 and an extension valve member
24 149 extend between the two housing members 146 and 147 and
are longitudinally movable relative thereto to perform the
26 various valving functions required.
27 Spaced seals 151 and 152 on the outer housing
28 member 146 engage the outer surface of the valve member 141
29 and 147 on either side of an annular chamber 153 which
surrounds t,he va]ve member 141 and 147. A por~ 154 connects
21 1315~94
1 the annular chamber 153 with a longitudinally extending
2 passage 156 through which fluid flows to inflate and deflate
3 the packers 33.
4 When the valve member 141 is positioned as illus-
trated in FIG. 6a, ports 169 in the valve member 149 are open
6 to the annular chamber 153 and the selector valve is in the
7 inflate/deflate position. The valve member 141 also provides
8 a seal 1~7 which engages the exterior surface of the inner
9 housing member 147 and which moves therealong when the valve
1~ is moved between its operation positions. Similarly, a seal
11 158 mounted adjacent to the lower end of the valve member 149
12 engages and provides a running seal with the outer surface
13 of the inner housing member 147.
14 Between the seal 157 and piston head assembly 121,
the valve member is sized to provide clearance with the
16 exterior surface of the inner housing member 147. The valve
17 member also provides an annular chamber 159 surrounding the
18 inner housing member 147 between the seals 157 and 158.
19 The upper end of the inner housing member 147 is
provided with a central passage 161 extending to an end 162.
21 A second longitudinal passaqe 163 extends up along the inner
22 housing member to an end 164 spaced from the end 162 so that
23 the two passages 161 and 163 are not directly connected.
24 First ports 166 are formed in the wall of the inner housing
member 147 at a location approximately midway along the
26 length of the passage 161. Second ports 167 also extend
27 through the wall of the inner housing member 147 substantial-
28 ly adjacent to the lower end of the passage 161. A third set
29 of ports 168 extend through the wall of the inner housing
member 147 substantially adjacent to the upper end of the
31 passage 163.
32 In the run-in position illustrated in FIG. 6a, the
33 ports 169 are positioned adjacent to the annular chamber 153
34 and communi,cation is provided through the ports 166, 169, and
22 13151~
1 154 to the inflate/deflate passage 156. In such position,
2 the packers can be inflated or deflated. In such position,
3 however, the seal 158 engages the portion of the inner
4 housing member between the ends of the two passages 161 and
163 so the remainder of the tool is isolated from the liquid
6 pressure in the upper portion of the tool.
7 When the valve member 141 is moved to the circulat-
8 ing position illustrated in FIG. 6b, the port 169 is spaced
9 from the annular chamber 153 so the packer inflate/deflate
passage 156 is isolated and the packers remain inflated. In
11 such position, the port 169 is in communication with the
12 annular chamber 159 and fluid flow is provided thereto
i3 through the ports 168, which are then located below the seal
14 157. In such condition, fluid pumped down to the tool passes
through the port 169 and through the circulation port 35
16 formed in the outer housing member 146. Also in such valve
17 position, the zone between the packers is connected to the
18 port 35.
19 The valve member 141 is also movable to a third or
inject position illustrated in FIG. 6c in which the port 169
21 is isolated from the interior passage 163 by the seals 157
22 and 158. However, in this position, communication is pro-
23 vided with the lower passage 163 through the ports 168, which
24 are then located above the seal 157. The time delay selector
valve is therefore operable in three different positions to
26 perform in sequence the various operations required for the
27 treatment of the well.
28 FIG. 7 is an enlarged, fragmentary view illustrat-
29 ing the connection between the selector valve and the packer
subassembly illustrated in FIG. 8. The packer assembly is
31 connected to the lower end of the selector valve assembly 32
32 by a tubular coupler 176 threaded into the lower end of the
33 outer housing member 146. The coupling provides the passage
3~ 34, which is open to and in communication with the second
23 131~
1 passage 163 in the inner housing member 147. The coupling
2 also provides a lateral port 177 interconnecting the inflate-
3 deflate passage 156 and a passage 178 along which fluid flows
4 to inflate and deflate the packers during such phases of the
tool operation.
6 Referring now to FIG. 8, the coupling member
7 extends down along the tool through an upper inflatable
8 packer 33, which is formed of a tube of elastomeric material
9 clamped at its upper end ~t 181 and at its lower end 182 to
the exterior of the tubular coupler 176. The upper inflat-
11 able packer 33 is connected to the inflate/deflate passage
12 178 by a lateral port 183 open to the interior thereof.
13 Therefore, when the selector valve is in the inflate or
14 deflate position, pressure communication is provided to the
interior of the packer for inflation or deflation thereof.
16 The tubular coupler is also provided with a second
17 inflate/deflate passage 184 which is spaced from the
18 inflate/deflate passage 178 and is also connected to the
19 interior of the upper packer 33 through a port 186. The
inflate/deflate passage 184 is connected at its lower end to
21 an additional inflate/deflate passage 187 formed of a tubular
22 member which extends between the upper and lower packers.
23 In FIG. 8, only one of the packers is illustrate in order to
24 simplify the drawings; however, it should be unders~ood that
a lower packer similar to the upper packer 33 illustrated in
26 FIG. 8 is usually provided at the lower end of the tool and
27 is inflated and deflated through the inflate/deflate passage
28 187.
29 The passage 3el is open to the zone between the two
packers through a port 191. A passage system 189 is aiso
31 provided to bypass the packers and connect the portion of the
32 well above the upper packer to the portion of the well below
33 the lower packer, even when the zone between the packers is
,.
24
131~94
1 isolated from the remainder of the well. In order to simpli~
2 fy the drawing, the passage system 189 is only illustrated
3 in the schematic FIGS. 9 through 14.
4 Operation
FIGS. 9 through 14 schematically illustrate the
6 sequence of operations of the tool when a well treatment is
7 to be performed. In each instance, the corresponding condi-
8 tion of the J-lock cam assembly 29 and the weight indication
9 are indicated by the weight scale 16.
Referring now to FIGS. 9, 9a, and gb, the tool is
11 schematically represented in its run-in condition. In such
12 condition, the tool is lowered into the well by lowering the
13 support tube 11 into the well with the tool secured on the
14 end thereof. During the run-in, the drag valve assembly 27
is held in the open position by the frictional drag of the
16 leaf springs 28 along the surface of the well. Consequently,
17 the liquid being pumped down to the tool is vented to the
18 environment through the drag v~lve 27. Further, during the
19 run-in, the time delay assembly 3l remains in its extended
position and the follower projection 95 is positioned in the
21 upper pocket 101. Consequently, the selector valve port 169
22 is open to the inflate/deflate passage 156. Since the
23 internal pressure within the tool is equal to the surrounding
24 pressure, the packers 33 remain deflated.
As the tool is lowered into the well, the weight
26 indicated by the weight scale 16 is monitored by the operator
27 and increases as the tool is lowered to greater depth.
28 ~uring the lowering of the tool, the operator also monitors
29 the depth of the tool indicated by the measuring device 17,
illustrated in FlG. 1.
~5 131~94
1 In many instances, a tube end locator (not shown,
2 but known to those skilled in the art) is also provided at
3 the upper end of the tool so that the operator can establish
4 when the tool is at the lower end of the production tube and
S correct the depth measurement provided by the measuring
6 device 17 to compensate for stretching the tube 11 and also
/ any slippage which might occur. This permits the operator
8 to accurately locate the tool at the strata which is to be
9 treated.
As the too approaches the position at the strata
11 to be treated, the weight reading 16a on the weight scale 16
12 is logged by the operator. That weight reading will be less
13 than the actual weight of the tool and the string being
14 supported by the grippers 14 because of the frictional drag
of the tube and the tocl as they are moving down along the
16 well surface.
17 Generally, the operator lowers the tool to a
18 position a few feet below the position in which the treatment
19 is to occur before stopping the tool. The operator then
reverses the grippers and raises the tool to the location in
21 whlch treatment is to occur. As the tool is being raised
22 the few feet back to the treatment position, the operator
23 also notes the weight indication 16b under a raising condi-
24 tion, which is greater than the run-in weight 16a, again due
to the frictional drag of the string.
26 Such raising movement causes the drag valve 27 to
27 move down along the tool to the closed position illustrated
28 in FIG. 10. The operator will note that the previously-noted
29 down-load 16a indicated during run-in will increase, as
indicated at 16b in FI~. iOb, as the tool is raised a short
31 distance ~ack to the treatment position.
32 After the tool is properly positioned at the
33 treatment location, the rate of flow of the fluid to the tool
34 is increased. This ~roduces a sufficient pressure
26 ~31~19~
1 differential across the piston head 59 to move the piston
2 down, closing the equalizing valve 26. Since the equalizing
3 valve 26 and the drag valve 27 are closed, the pressure
4 within the tool increases, causing inflation of the packers
33, as indicated in FIG. 10.
6 The operator then increases the force exerted by
7 the grippers to increase the tension in the tube 11 to verify
8 that the packers have in fact been inflated. Since the
9 pac~ers lock the tool against movement along the well when
they are inflated, increased tension will cause an increase
11 in the weight reading indicated by the arrow 16c beyond the
12 up-load reading indicated at 16b.
13 In some instances, the tool may encounter obstacles
14 during the run-in operation which cause the J-lock assembly
and the selector valve to move to an inject position in which
16 the follower projection is located within the pocket 102.
17 This does not present a problem if the tool is not extended
18 after the tool is raised up a short distance back to the
19 treatment position. The pressure within the tool causes
extension of the selector valve due to its action against
21 the area of the inner housing member 147. This returns the
22 selector valve to the extended position in which the follower
23 projection 95 is in the pocket 101.
24 Since the weight of the tool is not supported in
that instance, and since the extension force produced by the
26 tool pressure is relatively small, the pressure above the
27 piston head 123 of the time delay assembly 31 remains below
28 the pressure required to move the sleeve valve 134 a~ainst
29 the action of the springs 136 so the large orifice assembiy
146 remains open, permitting substantially free travel of the
31 time delay valve assembly 31 to its extended position for
32 proper inflation of the packers.
33 After the packers are properly inflated, as deter-
34 mined by the weight indication 16c, the load supported by the.
131~9~
1 grippers 14 is reduced and the tool moves to a position
2 illustrated in FIG. 11, in which the selector valve assembly
3 moves downwardly relative to the tool body, causing the
4 follower projection 95 to move along the path 103 into the
pocket 102, indicated in FIG. lla. This permits the testing
6 of the strata to determine if it will accept fluid. This
7 movement of the selector valve isolates the inflate/deflate
8 passage 156 so the packers 33 remain in their inflated
9 condition and continue to isolate the zone of the well
therebetween from the remaining zones of the weli. A weight
11 indication 16d less than the run-in weight 16a establishes
12 that the packers remain inflated.
13 The movement of the upper portions of the tool in
14 the downward direction tends to cause the drag valve to move
lS upwardly to its upward limit position, as illustrated in FIG.
16 11, but the downward movement of the selector valve positions
17 the ports 87 so that they are closed by the lower housing
18 assembly of the tool. Therefore, any liquid or other fluid
19 pumped dowrl the tube 11 into the tool is directed to the zone
between the packers. The operator at this time determines
21 whether or not the strata, which is isolated from the remain-
22 der of the well and which is to be treated, will accept
23 fluid.
24 It should be noted that when the tool string is
lowered to the position of FIG. 11, the lower end of the
26 piston member 58 engages a houlder on the lower housing and
27 the piston member is moved back to its upper position within
28 the equalizer valve assembly. However, the equalizer valve
29 remains closed because the port 64 is closed.
At the completion of the injecting iesting opera-
31 tion, the rate of flow of the fluid down to the tool is
32 reduced and the powered grippers 14 are operated to raise the
33 upper portion of the tool relative to the lower portion in
34 a sequence which positions tne tool in the position for
28 ~.3~94
1 spotting the treatment fluid indicated in FIG. 12. ~y
2 increasing the tension to a value above the up-load 16b, the
3 operator is assured that sufficient tension is present to
4 extend the upper portion of the tool relative to the lower
portion.
6 Substantially free travel is provided until the
7 tool extends beyond the location indicated by the line 108,
8 since the initial portion of extension occurs while the
9 damper piston head portion 123 and the sleeve valve 134 are
moving along the lower cylinder portion 119, which is suffi-
11 ciently large to allow fluid to bypass the piston assembly.
12 When the position indicated by the line 108 is
13 reached, the piston assembly moves into the upper cylinder
14 portion 116 and continued upward movement of the piston
assembly requires flow through the orifices. The rate of
16 upward movement, however, causes sufficient differential
17 pressure to occur across the sleeve valve 134 to cause it to
18 move against the action of the springs 136 to close the
19 larger orifice assembly 126. Thereafter, the only open path
of flow past the piston is provided by the small orifice
21 assembly 127, which is sized to require at least about three
22 minutes for the valve to mGve to a fully extended position.
23 As soon as the load on the grippers increases, as indicated
24 at 16e in FIG. 12b, the operator is provided with an indica-
tion that the damping or time delay function is commenced.
26 The operator then continues to raise the upper portion of the
27 tool for a period of time less than two minutes to ensure
28 that the selector valve does not fully exter.d.
29 During this upward movement of the tool, the
follower projection 95 moves up along the cam surfaces along
31 the path 106 and is positioned alongside of the island cam
32 107. The operator then decreases the tension on the support
33 tube 11 and causes the follower projection 95 to move down
34 along the ,cam surface along the path 109 into the J-loc~
29
1 3 ~
1 position at 99g. In such position, the port 169 in the
2 selector valve is in alignment with the circulation port 35
3 in the lower tool housing. Such downward movement may also
4 cause the drag valve 27 to open, as indicated in FIG. 12.
Also, the upper housing assembly of the equali~ing valve
6 assembly 26 moves to its compressed position during this
7 downward movement. A weight indication 16d less than the
8 run-in weight 16a again confirms that the packers are still
9 inflated.
The spotting operation is commenced by moving the
11 selector valve 19, illustrated in FIG. 1, to connect the
12 treatment liquid reservoir 22 to the pump 18 so that the
13 treatment fluid is pumped down the support tube 11 to the
14 tool and the inflation fluid is displaced from the tube
through the port 35 and/or the ports 87, both of which are
16 open to the environment. This spotting operation functions
17 to expel the inflation fluid from the tube 11 and to position
18 the leading edge of the treatment fluid at the tool for
19 subsequent injection.
The operator then operates the power grippers to
21 increase the tension in the support tube 11 to raise the
22 follower projection 95 out of the spotting pocket 99g until
23 it moves past the position indicated by the line 108 in FIG.
24 13a along the path 111. The fact that the tool has been
raised into the damping zone above the position of 108 is
26 again indicated by an increase in the weight to 16f on the
27 grippers. Here again, the tension is only maintair.ed for
28 less than two minutes of the three-minute time delay provided
29 by the time delay assembly to ensure that the valve does not
move back to the inflate/deflate position.
31 The load on the grippers is then decreased, causing
32 the follower projection 95 to move down along the path 110
33 back to the lower pocket 102. This positions the valve for
34 injection, as illustrated in FIG. 13. Again, a weight
30 131~
1 reading 16d less than the run-in weight 16a establishes that
2 the packers remain inflated. The treatment fluid is then
3 pumped down to the tool and is injected into the strata
4 between the two packers 33.
At the completion of the injection phase of the
6 operation, the operator shuts off the pump and increases the
7 load on the grippers to a value 16g greater than the up-load
8 value indicated at 16b to again move the follower projection
9 95 up along the cam surface 99 along the path 106. When the
damper again moves into the damping position, the tension is
11 maintained on the support tube for more ~han three minutes,
12 so the follower projection 95 moves back to the upper pocket
13 101.
14 Once the selector valve reaches the deflate posi-
tion, the inflate/deflate passage 156 is opened through the
16 ports 63 and 64 and the pressure is equalized through the
17 equalizing valve 26. This causes the packers 33 to deflate.
18 A decrease in weight reading from 16f back to the pull-up
19 weight 16b establishes that the packers are deflated.
At this time, the tool can be moved to another
21 location where treatment is required and the cycle can be
22 repeated, or the tool can be raised up out of the well.
23 FIGS. 15 through 15c illustrate a novel and im-
24 proved method of producing an internal camming surface along
the inside of a relatively long and relatively narrow tubular
26 member. As a first step in the formation of the camming
27 surface, a solid cylindrical mandrel 201 is selected having
28 a diameter equal to the maximum diameter of the camming
29 surfaces. The mandrel 201 ls then machined along its outer
surface to cut into the outer surface thereof the required
31 camming surface structure. For example, in producing the J-
32 lock cam assembly, a series of cam groo~es 202 are cut into
33 the outer surface of the mandrel 201, as illustrated in FIG.
34 15a. Once,the camming grooves have been cut into the outer
31 131519~
1 surface of the mandrel 201, the mandrel is inserted into the
2 outer tube 203. The mandrel is connected to the outer
3 tubular sleeve 193 by button welds 204 which fill openings
4 previously formed in the tubular sleeve 203. Such button
welds are appropriately placed to provide a connection
6 between any island cam portions, such as the island portions
7 104 and 107, and also to connect other portions of the
8 mandrel to the sleeve. Thereafter, the central portion of
9 the mandrel is bored out, as illustrated in FIG. 15c to a
diameter which exceeds the inner diameter of the cam grooves.
11 In this way, external machining can be provided to produce
12 intricate camming surfaces along the inside of a relatively
13 narrow and relatively ;ong tube.
14 With this invention, a treatment tool is provided
which can be controlled with certainty from the well head by
l6 noting changes in the load on the power grlppers as indicated
17 by the weighing scale 16. ~n each step of the operation,
18 changes in the weight indicated by the scale 16 provide the
19 operator with an indication that the previous portion of the
cycle has been properly and successfully completed and that
21 the tool is in proper condition for a subsequent operation.
22 Because weights, and not distances, are utili~ed tc conlrol
23 the operation of the tool, any slippage occurring in the
24 depth measuring device 17 or stretching of the support tube
11 do not adversely affect the operation of the tool.
26 Further, it is not necessary to rotate the tube to control
27 the operation of the tool. Still further, it is not neces-
28 sary to rely upon elecrronics or dropping balls to determine
29 the condition of the tool and the simple weight scale 16
provides the operator with all of the information he needs
31 to have concerning the operation of the tool through a
32 complete cycle. Still further, with this inventlon a small
33 diameter tool is provided that can fit a relatively small
32 131~94
1 production tube and operate in a casing having a substantial-
2 ly greater diameter.
3 Although the preferred embodiment of this invention
4 has been shown and described, it should be understood that
various modifications and rearrangements of the parts may be
6 resorted to without departing from the scope of the invention
7 as disclosed and claimed herein.
